Heat the oil in a saucepan over medium heat. Add the jackfruit and chiles and cook, stirring, for 3 minutes. Stir in the barbecue sauce, tamari, mustard, paprika, liquid smoke, onion powder, and salt and pepper to taste. Cook, stirring occasionally, to heat through and blend the flavors, about 8 minutes. Mix well, adding a little water if the mixture is too dry. Taste and adjust the seasonings, if needed. When ready to serve, spoon the mixture onto the rolls and serve hot.